Leaves of Taxus with cuticle micromorphology from the Early Cretaceous of eastern Inner Mongolia, Northeast China
2022
Dong, Chong | Shi, Gongle | Herrera, Fabiany | Wang, Yongdong | Wang, Zixi | Zhang, Bole | Xu, Xiaohui | Herendeen, Patrick S. | Crane, Peter R.
The Early Cretaceous Huolinhe Formation in eastern Inner Mongolia, northeastern China has yielded abundant and diverse plant fossils, to which we here add a new species of Taxus based on exceptionally well-preserved, lignified leaves from the Gucheng open-cast coal mine. Taxus huolingolensis sp. nov. has linear leaves with a lamina that tapers to an acute to mucronate apex, and narrows into a decurrent, stalk-like base. The midrib is prominently raised on the abaxial leaf surface. The abaxial leaf cuticle bears dense, short, isodiametric papillae and has two lateral stomatal bands, each of which contains 3–5 short, discontinuous longitudinal rows of stomata. Stomata are longitudinally oriented, amphicyclic, with two polar subsidiary cells and 2–4 lateral subsidiary cells. Each stoma has a more-or-less transversely elongated papillate stomatal ring around the stomatal pit on the outer cuticle surface. Taxus huolingolensis sp. nov. closely resembles leaves of extant Taxus in gross morphology as well as cuticle micromorphology, and within the genus is most similar to the North American species T. brevifolia. Like the leaves of other species of Taxus from the Mesozoic, Taxus huolingolensis sp. nov. has narrower stomatal bands with fewer stomatal rows in each stomatal band compared to the living species of the genus. The discovery of T. huolingolensis adds to our knowledge of Mesozoic Taxaceae and suggests that Taxus has been diverse since the Early Cretaceous.
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